var arr = [1,4,2,3,0,5];
// Using the given array, arr, generate the pairwise sums of the first number
// in the array with each of the rest of the numbers in the array, that is:
// 1 + 4 = 5;
// 1 + 2 = 3;
// 1 + 3 = 4;
// ... etc.